#include "llvm/Function.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Compiler.h"
#include "llvm/ADT/BitVector.h"
+#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallSet.h"
#include <algorithm>
using namespace llvm;
-STATISTIC(NumSpills, "Number of register spills");
-STATISTIC(NumPSpills,"Number of physical register spills");
-STATISTIC(NumReMats, "Number of re-materialization");
-STATISTIC(NumDRM , "Number of re-materializable defs elided");
-STATISTIC(NumStores, "Number of stores added");
-STATISTIC(NumLoads , "Number of loads added");
-STATISTIC(NumReused, "Number of values reused");
-STATISTIC(NumDSE , "Number of dead stores elided");
-STATISTIC(NumDCE , "Number of copies elided");
-STATISTIC(NumDSS , "Number of dead spill slots removed");
+STATISTIC(NumSpills , "Number of register spills");
+STATISTIC(NumPSpills , "Number of physical register spills");
+STATISTIC(NumReMats , "Number of re-materialization");
+STATISTIC(NumDRM , "Number of re-materializable defs elided");
+STATISTIC(NumStores , "Number of stores added");
+STATISTIC(NumLoads , "Number of loads added");
+STATISTIC(NumReused , "Number of values reused");
+STATISTIC(NumDSE , "Number of dead stores elided");
+STATISTIC(NumDCE , "Number of copies elided");
+STATISTIC(NumDSS , "Number of dead spill slots removed");
+STATISTIC(NumCommutes, "Number of instructions commuted");
namespace {
enum SpillerName { simple, local };
-
- static cl::opt<SpillerName>
- SpillerOpt("spiller",
- cl::desc("Spiller to use: (default: local)"),
- cl::Prefix,
- cl::values(clEnumVal(simple, " simple spiller"),
- clEnumVal(local, " local spiller"),
- clEnumValEnd),
- cl::init(local));
}
+static cl::opt<SpillerName>
+SpillerOpt("spiller",
+ cl::desc("Spiller to use: (default: local)"),
+ cl::Prefix,
+ cl::values(clEnumVal(simple, " simple spiller"),
+ clEnumVal(local, " local spiller"),
+ clEnumValEnd),
+ cl::init(local));
+
//===----------------------------------------------------------------------===//
// VirtRegMap implementation
//===----------------------------------------------------------------------===//
Virt2SplitKillMap(0), ReMatMap(NULL), ReMatId(MAX_STACK_SLOT+1),
LowSpillSlot(NO_STACK_SLOT), HighSpillSlot(NO_STACK_SLOT) {
SpillSlotToUsesMap.resize(8);
+ ImplicitDefed.resize(MF.getRegInfo().getLastVirtReg()+1-
+ TargetRegisterInfo::FirstVirtualRegister);
grow();
}
Virt2SplitMap.grow(LastVirtReg);
Virt2SplitKillMap.grow(LastVirtReg);
ReMatMap.grow(LastVirtReg);
+ ImplicitDefed.resize(LastVirtReg-TargetRegisterInfo::FirstVirtualRegister+1);
}
int VirtRegMap::assignVirt2StackSlot(unsigned virtReg) {
void VirtRegMap::addSpillSlotUse(int FI, MachineInstr *MI) {
if (!MF.getFrameInfo()->isFixedObjectIndex(FI)) {
- assert(FI >= 0 && "Spill slot index should not be negative!");
- SpillSlotToUsesMap[FI-LowSpillSlot].insert(MI);
+ // If FI < LowSpillSlot, this stack reference was produced by
+ // instruction selection and is not a spill
+ if (FI >= LowSpillSlot) {
+ assert(FI >= 0 && "Spill slot index should not be negative!");
+ assert((unsigned)FI-LowSpillSlot < SpillSlotToUsesMap.size()
+ && "Invalid spill slot");
+ SpillSlotToUsesMap[FI-LowSpillSlot].insert(MI);
+ }
}
}
int FI = MO.getIndex();
if (MF.getFrameInfo()->isFixedObjectIndex(FI))
continue;
+ // This stack reference was produced by instruction selection and
+ // is not a spill
+ if (FI < LowSpillSlot)
+ continue;
+ assert((unsigned)FI-LowSpillSlot < SpillSlotToUsesMap.size()
+ && "Invalid spill slot");
SpillSlotToUsesMap[FI-LowSpillSlot].erase(MI);
}
MI2VirtMap.erase(MI);
MachineRegisterInfo *RegInfo;
const TargetRegisterInfo *TRI;
const TargetInstrInfo *TII;
+ DenseMap<MachineInstr*, unsigned> DistanceMap;
public:
bool runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM) {
RegInfo = &MF.getRegInfo();
return true;
}
private:
+ void TransferDeadness(MachineBasicBlock *MBB, unsigned CurDist,
+ unsigned Reg, BitVector &RegKills,
+ std::vector<MachineOperand*> &KillOps);
bool PrepForUnfoldOpti(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &MII,
std::vector<MachineInstr*> &MaybeDeadStores,
AvailableSpills &Spills, BitVector &RegKills,
std::vector<MachineOperand*> &KillOps,
VirtRegMap &VRM);
+ bool CommuteToFoldReload(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator &MII,
+ unsigned VirtReg, unsigned SrcReg, int SS,
+ BitVector &RegKills,
+ std::vector<MachineOperand*> &KillOps,
+ const TargetRegisterInfo *TRI,
+ VirtRegMap &VRM);
void SpillRegToStackSlot(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &MII,
int Idx, unsigned PhysReg, int StackSlot,
return false;
bool FoundUse = false, Done = false;
- MachineBasicBlock::iterator E = NewDef;
+ MachineBasicBlock::iterator E = &NewDef;
++I; ++E;
for (; !Done && I != E; ++I) {
MachineInstr *NMI = I;
if (Reg == 0)
continue;
- if (RegKills[Reg]) {
+ if (RegKills[Reg] && KillOps[Reg]->getParent() != &MI) {
// That can't be right. Register is killed but not re-defined and it's
// being reused. Let's fix that.
KillOps[Reg]->setIsKill(false);
static void ReMaterialize(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &MII,
unsigned DestReg, unsigned Reg,
+ const TargetInstrInfo *TII,
const TargetRegisterInfo *TRI,
VirtRegMap &VRM) {
- TRI->reMaterialize(MBB, MII, DestReg, VRM.getReMaterializedMI(Reg));
+ TII->reMaterialize(MBB, MII, DestReg, VRM.getReMaterializedMI(Reg));
MachineInstr *NewMI = prior(MII);
for (unsigned i = 0, e = NewMI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = NewMI->getOperand(i);
MachineBasicBlock::iterator MII = MI;
if (NewOp.StackSlotOrReMat > VirtRegMap::MAX_STACK_SLOT) {
- ReMaterialize(*MBB, MII, NewPhysReg, NewOp.VirtReg, TRI, VRM);
+ ReMaterialize(*MBB, MII, NewPhysReg, NewOp.VirtReg, TII, TRI,VRM);
} else {
TII->loadRegFromStackSlot(*MBB, MII, NewPhysReg,
NewOp.StackSlotOrReMat, AliasRC);
/// This enables unfolding optimization for a subsequent instruction which will
/// also eliminate the newly introduced store instruction.
bool LocalSpiller::PrepForUnfoldOpti(MachineBasicBlock &MBB,
- MachineBasicBlock::iterator &MII,
+ MachineBasicBlock::iterator &MII,
std::vector<MachineInstr*> &MaybeDeadStores,
- AvailableSpills &Spills,
- BitVector &RegKills,
- std::vector<MachineOperand*> &KillOps,
- VirtRegMap &VRM) {
+ AvailableSpills &Spills,
+ BitVector &RegKills,
+ std::vector<MachineOperand*> &KillOps,
+ VirtRegMap &VRM) {
MachineFunction &MF = *MBB.getParent();
MachineInstr &MI = *MII;
unsigned UnfoldedOpc = 0;
unsigned UnfoldVR = 0;
int FoldedSS = VirtRegMap::NO_STACK_SLOT;
VirtRegMap::MI2VirtMapTy::const_iterator I, End;
- for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ++I) {
+ for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ) {
// Only transform a MI that folds a single register.
if (UnfoldedOpc)
return false;
UnfoldVR = I->second.first;
VirtRegMap::ModRef MR = I->second.second;
+ // MI2VirtMap be can updated which invalidate the iterator.
+ // Increment the iterator first.
+ ++I;
if (VRM.isAssignedReg(UnfoldVR))
continue;
// If this reference is not a use, any previous store is now dead.
VRM.assignVirt2Phys(UnfoldVR, UnfoldPR);
VRM.virtFolded(VirtReg, FoldedMI, VirtRegMap::isRef);
MII = MBB.insert(MII, FoldedMI);
+ InvalidateKills(MI, RegKills, KillOps);
VRM.RemoveMachineInstrFromMaps(&MI);
MBB.erase(&MI);
return true;
}
- delete NewMI;
+ MF.DeleteMachineInstr(NewMI);
}
}
return false;
}
+/// CommuteToFoldReload -
+/// Look for
+/// r1 = load fi#1
+/// r1 = op r1, r2<kill>
+/// store r1, fi#1
+///
+/// If op is commutable and r2 is killed, then we can xform these to
+/// r2 = op r2, fi#1
+/// store r2, fi#1
+bool LocalSpiller::CommuteToFoldReload(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator &MII,
+ unsigned VirtReg, unsigned SrcReg, int SS,
+ BitVector &RegKills,
+ std::vector<MachineOperand*> &KillOps,
+ const TargetRegisterInfo *TRI,
+ VirtRegMap &VRM) {
+ if (MII == MBB.begin() || !MII->killsRegister(SrcReg))
+ return false;
+
+ MachineFunction &MF = *MBB.getParent();
+ MachineInstr &MI = *MII;
+ MachineBasicBlock::iterator DefMII = prior(MII);
+ MachineInstr *DefMI = DefMII;
+ const TargetInstrDesc &TID = DefMI->getDesc();
+ unsigned NewDstIdx;
+ if (DefMII != MBB.begin() &&
+ TID.isCommutable() &&
+ TII->CommuteChangesDestination(DefMI, NewDstIdx)) {
+ MachineOperand &NewDstMO = DefMI->getOperand(NewDstIdx);
+ unsigned NewReg = NewDstMO.getReg();
+ if (!NewDstMO.isKill() || TRI->regsOverlap(NewReg, SrcReg))
+ return false;
+ MachineInstr *ReloadMI = prior(DefMII);
+ int FrameIdx;
+ unsigned DestReg = TII->isLoadFromStackSlot(ReloadMI, FrameIdx);
+ if (DestReg != SrcReg || FrameIdx != SS)
+ return false;
+ int UseIdx = DefMI->findRegisterUseOperandIdx(DestReg, false);
+ if (UseIdx == -1)
+ return false;
+ int DefIdx = TID.getOperandConstraint(UseIdx, TOI::TIED_TO);
+ if (DefIdx == -1)
+ return false;
+ assert(DefMI->getOperand(DefIdx).isRegister() &&
+ DefMI->getOperand(DefIdx).getReg() == SrcReg);
+
+ // Now commute def instruction.
+ MachineInstr *CommutedMI = TII->commuteInstruction(DefMI, true);
+ if (!CommutedMI)
+ return false;
+ SmallVector<unsigned, 2> Ops;
+ Ops.push_back(NewDstIdx);
+ MachineInstr *FoldedMI = TII->foldMemoryOperand(MF, CommutedMI, Ops, SS);
+ // Not needed since foldMemoryOperand returns new MI.
+ MF.DeleteMachineInstr(CommutedMI);
+ if (!FoldedMI)
+ return false;
+
+ VRM.addSpillSlotUse(SS, FoldedMI);
+ VRM.virtFolded(VirtReg, FoldedMI, VirtRegMap::isRef);
+ // Insert new def MI and spill MI.
+ const TargetRegisterClass* RC = MF.getRegInfo().getRegClass(VirtReg);
+ TII->storeRegToStackSlot(MBB, &MI, NewReg, true, SS, RC);
+ MII = prior(MII);
+ MachineInstr *StoreMI = MII;
+ VRM.addSpillSlotUse(SS, StoreMI);
+ VRM.virtFolded(VirtReg, StoreMI, VirtRegMap::isMod);
+ MII = MBB.insert(MII, FoldedMI); // Update MII to backtrack.
+
+ // Delete all 3 old instructions.
+ InvalidateKills(*ReloadMI, RegKills, KillOps);
+ VRM.RemoveMachineInstrFromMaps(ReloadMI);
+ MBB.erase(ReloadMI);
+ InvalidateKills(*DefMI, RegKills, KillOps);
+ VRM.RemoveMachineInstrFromMaps(DefMI);
+ MBB.erase(DefMI);
+ InvalidateKills(MI, RegKills, KillOps);
+ VRM.RemoveMachineInstrFromMaps(&MI);
+ MBB.erase(&MI);
+
+ ++NumCommutes;
+ return true;
+ }
+
+ return false;
+}
+
/// findSuperReg - Find the SubReg's super-register of given register class
/// where its SubIdx sub-register is SubReg.
static unsigned findSuperReg(const TargetRegisterClass *RC, unsigned SubReg,
++NumStores;
}
+/// TransferDeadness - A identity copy definition is dead and it's being
+/// removed. Find the last def or use and mark it as dead / kill.
+void LocalSpiller::TransferDeadness(MachineBasicBlock *MBB, unsigned CurDist,
+ unsigned Reg, BitVector &RegKills,
+ std::vector<MachineOperand*> &KillOps) {
+ int LastUDDist = -1;
+ MachineInstr *LastUDMI = NULL;
+ for (MachineRegisterInfo::reg_iterator RI = RegInfo->reg_begin(Reg),
+ RE = RegInfo->reg_end(); RI != RE; ++RI) {
+ MachineInstr *UDMI = &*RI;
+ if (UDMI->getParent() != MBB)
+ continue;
+ DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(UDMI);
+ if (DI == DistanceMap.end() || DI->second > CurDist)
+ continue;
+ if ((int)DI->second < LastUDDist)
+ continue;
+ LastUDDist = DI->second;
+ LastUDMI = UDMI;
+ }
+
+ if (LastUDMI) {
+ const TargetInstrDesc &TID = LastUDMI->getDesc();
+ MachineOperand *LastUD = NULL;
+ for (unsigned i = 0, e = LastUDMI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = LastUDMI->getOperand(i);
+ if (!MO.isRegister() || MO.getReg() != Reg)
+ continue;
+ if (!LastUD || (LastUD->isUse() && MO.isDef()))
+ LastUD = &MO;
+ if (TID.getOperandConstraint(i, TOI::TIED_TO) != -1)
+ return;
+ }
+ if (LastUD->isDef())
+ LastUD->setIsDead();
+ else {
+ LastUD->setIsKill();
+ RegKills.set(Reg);
+ KillOps[Reg] = LastUD;
+ }
+ }
+}
+
/// rewriteMBB - Keep track of which spills are available even after the
/// register allocator is done with them. If possible, avid reloading vregs.
void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
std::vector<MachineOperand*> KillOps;
KillOps.resize(TRI->getNumRegs(), NULL);
+ unsigned Dist = 0;
+ DistanceMap.clear();
for (MachineBasicBlock::iterator MII = MBB.begin(), E = MBB.end();
MII != E; ) {
MachineBasicBlock::iterator NextMII = MII; ++NextMII;
unsigned Phys = VRM.getPhys(VirtReg);
RegInfo->setPhysRegUsed(Phys);
if (VRM.isReMaterialized(VirtReg)) {
- ReMaterialize(MBB, MII, Phys, VirtReg, TRI, VRM);
+ ReMaterialize(MBB, MII, Phys, VirtReg, TII, TRI, VRM);
} else {
const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
int SS = VRM.getStackSlot(VirtReg);
// We want to process implicit virtual register uses first.
if (MO.isImplicit())
+ // If the virtual register is implicitly defined, emit a implicit_def
+ // before so scavenger knows it's "defined".
VirtUseOps.insert(VirtUseOps.begin(), i);
else
VirtUseOps.push_back(i);
ReusedOperands.markClobbered(Phys);
unsigned RReg = SubIdx ? TRI->getSubReg(Phys, SubIdx) : Phys;
MI.getOperand(i).setReg(RReg);
+ if (VRM.isImplicitlyDefined(VirtReg))
+ BuildMI(MBB, &MI, TII->get(TargetInstrInfo::IMPLICIT_DEF), RReg);
continue;
}
RegInfo->setPhysRegUsed(PhysReg);
ReusedOperands.markClobbered(PhysReg);
if (DoReMat) {
- ReMaterialize(MBB, MII, PhysReg, VirtReg, TRI, VRM);
+ ReMaterialize(MBB, MII, PhysReg, VirtReg, TII, TRI, VRM);
} else {
const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
TII->loadRegFromStackSlot(MBB, &MI, PhysReg, SSorRMId, RC);
// physical registers that may contain the value of the spilled virtual
// register
SmallSet<int, 2> FoldedSS;
- for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ++I) {
+ for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ) {
unsigned VirtReg = I->second.first;
VirtRegMap::ModRef MR = I->second.second;
DOUT << "Folded vreg: " << VirtReg << " MR: " << MR;
+ // MI2VirtMap be can updated which invalidate the iterator.
+ // Increment the iterator first.
+ ++I;
int SS = VRM.getStackSlot(VirtReg);
if (SS == VirtRegMap::NO_STACK_SLOT)
continue;
InvalidateKill(InReg, RegKills, KillOps);
}
+ InvalidateKills(MI, RegKills, KillOps);
VRM.RemoveMachineInstrFromMaps(&MI);
MBB.erase(&MI);
Erased = true;
if (PhysReg &&
TII->unfoldMemoryOperand(MF, &MI, PhysReg, false, false, NewMIs)) {
MBB.insert(MII, NewMIs[0]);
+ InvalidateKills(MI, RegKills, KillOps);
VRM.RemoveMachineInstrFromMaps(&MI);
MBB.erase(&MI);
Erased = true;
// the value and there isn't an earlier def that has already clobbered
// the physreg.
if (PhysReg &&
- !TII->isStoreToStackSlot(&MI, SS) && // Not profitable!
- DeadStore->killsRegister(PhysReg) &&
- TII->unfoldMemoryOperand(MF, &MI, PhysReg, false, true, NewMIs)) {
- MBB.insert(MII, NewMIs[0]);
- NewStore = NewMIs[1];
- MBB.insert(MII, NewStore);
- VRM.addSpillSlotUse(SS, NewStore);
- VRM.RemoveMachineInstrFromMaps(&MI);
- MBB.erase(&MI);
- Erased = true;
- --NextMII;
- --NextMII; // backtrack to the unfolded instruction.
- BackTracked = true;
- isDead = true;
+ !TII->isStoreToStackSlot(&MI, SS)) { // Not profitable!
+ MachineOperand *KillOpnd =
+ DeadStore->findRegisterUseOperand(PhysReg, true);
+ // Note, if the store is storing a sub-register, it's possible the
+ // super-register is needed below.
+ if (KillOpnd && !KillOpnd->getSubReg() &&
+ TII->unfoldMemoryOperand(MF, &MI, PhysReg, false, true,NewMIs)){
+ MBB.insert(MII, NewMIs[0]);
+ NewStore = NewMIs[1];
+ MBB.insert(MII, NewStore);
+ VRM.addSpillSlotUse(SS, NewStore);
+ InvalidateKills(MI, RegKills, KillOps);
+ VRM.RemoveMachineInstrFromMaps(&MI);
+ MBB.erase(&MI);
+ Erased = true;
+ --NextMII;
+ --NextMII; // backtrack to the unfolded instruction.
+ BackTracked = true;
+ isDead = true;
+ }
}
}
if (unsigned SrcReg = TII->isStoreToStackSlot(&MI, StackSlot)) {
assert(TargetRegisterInfo::isPhysicalRegister(SrcReg) &&
"Src hasn't been allocated yet?");
+
+ if (CommuteToFoldReload(MBB, MII, VirtReg, SrcReg, StackSlot,
+ RegKills, KillOps, TRI, VRM)) {
+ NextMII = next(MII);
+ BackTracked = true;
+ goto ProcessNextInst;
+ }
+
// Okay, this is certainly a store of SrcReg to [StackSlot]. Mark
// this as a potentially dead store in case there is a subsequent
// store into the stack slot without a read from it.
MaybeDeadStores[StackSlot] = &MI;
// If the stack slot value was previously available in some other
- // register, change it now. Otherwise, make the register available,
- // in PhysReg.
- Spills.addAvailable(StackSlot, &MI, SrcReg, false/*don't clobber*/);
+ // register, change it now. Otherwise, make the register
+ // available in PhysReg.
+ Spills.addAvailable(StackSlot, &MI, SrcReg, false/*!clobber*/);
}
}
}
if (TII->isMoveInstr(MI, Src, Dst) && Src == Dst) {
++NumDCE;
DOUT << "Removing now-noop copy: " << MI;
+ SmallVector<unsigned, 2> KillRegs;
+ InvalidateKills(MI, RegKills, KillOps, &KillRegs);
+ if (MO.isDead() && !KillRegs.empty()) {
+ assert(KillRegs[0] == Dst);
+ // Last def is now dead.
+ TransferDeadness(&MBB, Dist, Src, RegKills, KillOps);
+ }
VRM.RemoveMachineInstrFromMaps(&MI);
MBB.erase(&MI);
Erased = true;
}
}
+ assert(PhysReg && "VR not assigned a physical register?");
RegInfo->setPhysRegUsed(PhysReg);
unsigned RReg = SubIdx ? TRI->getSubReg(PhysReg, SubIdx) : PhysReg;
ReusedOperands.markClobbered(RReg);
if (TII->isMoveInstr(MI, Src, Dst) && Src == Dst) {
++NumDCE;
DOUT << "Removing now-noop copy: " << MI;
+ InvalidateKills(MI, RegKills, KillOps);
VRM.RemoveMachineInstrFromMaps(&MI);
MBB.erase(&MI);
Erased = true;
}
}
ProcessNextInst:
+ DistanceMap.insert(std::make_pair(&MI, Dist++));
if (!Erased && !BackTracked) {
- for (MachineBasicBlock::iterator II = MI; II != NextMII; ++II)
+ for (MachineBasicBlock::iterator II = &MI; II != NextMII; ++II)
UpdateKills(*II, RegKills, KillOps);
}
MII = NextMII;
projects / oota-llvm.git / blobdiff